Using Genomics to Improve Reproduction Traits in Sheep

Reproduction traits are important but difficult to improve in sheep because they are lowly heritable and are recorded later in life. Genomic information can be used for genomic prediction of breeding values to increase the accuracy of selection. Alternatively, genomic information can be used to identify recessive lethal mutations, which cause embryonic losses. We investigated both uses of genomic information using 54k SNP in the Border Leicester, Merino and Polled Dorset breeds. Genomic prediction accuracy of three reproduction traits was greater when compared to pedigree methods, especially in less related animals. Furthermore, making use of both sire and ewe information in the reference set increased accuracies. Ten haplotypes carrying potential recessive lethal mutations were identified. One haplotype spanning 50 SNP alleles was significantly associated with litter size. The findings suggest genomic tools should be used to increase reproductive efficiency in sheep.